I've always viewed Stann as a mediocre name in MMA with an annoying military promotional backing him on story alone, but he really has improved with his fight against Silva. Yeah he lost the fight in a bad way, but his stand up was way more crisp than older fights I've seen of his, where he could easily be described as ungainly and awkward as a striker. He rocked Silva a few times to say the least and didn't appear awkward or sloppy any more. Props to him for that, knockout or no knockout.
That said, legitimate improvements aside, I don't think it's a good idea for him to keep fighting, he's just going to be a stepping stone for up and comers if he continues, and he ate enough nasty shots at the end of that fight to break his chins ability to take more in any future fight. I'd hang it up if I were him. He's a classy guy and looks like a genuinely good person, he could make a bigger impact helping folks in some sort of charity arena so long as he gets on it before becoming brain damaged, and he will, if he eats more damage like that - which is more likely to happen, after it happens the first time.